Tangential Radiography of 16" pipe

[mariolucas75]

What are pros and cons using Selenium for tangential radiography of NPS 16 " pipes typical thickness 9-12 mm range to find an internal or external corrosion () ?
Since selenium has a lower penetration ability ~ 25mm and the beam may travel along the chord inside the thickness which may have a length more 25 mm ... may it mean that beam will not make its way through onto the film ?


Thank you so much.

 

[LittleInch]

what's wrong with a UT probe?

Never heard of using radiography to determine corrosion before.

but you're prob better looking in the corrosion or QA forum.

 

[mariolucas75]

It has a corrosion deposit large enough 150 mm wide spot on pipe 30mm high

 

[akpipelineengr]

The typical application of tangential radiography is for external corrosion, particularly CUI. You aren't looking for penetration of the steel, only the insulation around the pipe. This gives you a tangential view of the pipe surface, from which you can see CUI damage due to the expansive characteristics of iron oxide compared to steel. It is typical to perform several tangential views, say 3,6, and 9 o'clock, on the pipe to characterize the corroded area.

I've not heard of tangential radiography for internal corrosion.

 

[NovaStark]

This article here seems to compare a few sources:

https://www.ndt.net/article/apcndt2006/papers/12.pdf

If you are specifically looking for general internal corrosion/erosion patterns where the order of magnitude is important, then you'd be better off asking a radiographic testing contractor.

I never used Selenium for radiography in the field, but the results for IR-192 is a standard one. So it really depends on what level of detail you need to get.